var timeout       = 500;
var closetimer    = 0;
var menuitem      = 0;

// open hidden layer
function openMenu(id)
{    
    // cancel close timer
    cancelCloseMenuTimer();
    // close old layer
    if(menuitem) menuitem.style.visibility = 'hidden';
    // get new layer and show it
    menuitem = document.getElementById(id);
    menuitem.style.visibility = 'visible';
}

// close showed layer
function closeMenu()
{
    if(menuitem) menuitem.style.visibility = 'hidden';
}

// go close timer
function closeMenuTimer()
{
    closetimer = window.setTimeout(closeMenu, timeout);
}

// cancel close timer
function cancelCloseMenuTimer()
{
    if(closetimer)
    {
        window.clearTimeout(closetimer);
        closetimer = null;
    }
}

// close layer when click-out
document.onclick = closeMenu;